Large pipe sections are commonly formed by bending large sheets of metal together and then joining the edges of the metal sheet by use of a weld bead. The weld bead is commonly formed by a submerged arc welding process; however, other types of welding processes can be used. After the pipe has been formed, the interior of the pipe is inspected to determine the quality of the weld bead. One common problem encountered after the formation of the weld bead is undercut. Undercut can occur when the welding arcs melt away the edges of the metal sheet and the weld bead does not completely fill in this melted area, thereby leaving a notch or other depressed region between the weld metal and the edge of the metal sheet. The existence of undercut in the weld bead is considered a defect that can result in the formed pipe being declared defective for a particular use.
Various submerged arc welding fluxes and welding techniques have been developed to minimize the occurrence and/or degree of undercut during a welding process. Typically the occurrence and degree of undercut are visually measured by an individual physically moves through the formed pipe and visually inspects the weld bead with a light. In view of the fact that an individual is inspecting the formed weld bead, the determination regarding the severity and amount of undercut can be somewhat subjective. As such, it can often be difficult to effectively determine whether a certain consumable electrode, particular welding setting and/or particular welding flux result in a greater or lesser degree of undercut during the formation of a pipe.
In view of the state of the art of pipe welding, there is a need for standardized method for accurately evaluating the occurrence and/or degree of undercut of a weld bead.